Current variable speed fan drives typically include a fixed sheave and a movable sheave which is coupled by splines to a drive shaft. This splined connection must be lubricated with oil or grease. The translational movement of the parts makes it difficult to contain the lubricant with seals. Leaking lubricant causes premature spline wear and lubricant leaking onto the V-belts causing premature belt wear.
U.S. Pat. No. 4,378,221, issued to Huff et al. in March 1983 shows a torque cam assembly for a variable speed belt drive having a fixed sheave and an axially slidable sheave. A collar is mounted on the drive shaft and has a plurality of cams thereon, and a cam follower with generally axially protruding members is mounted on the slidable sheave for cooperating with the cams on the collar. Wear elements on the members contact the cams on the collar. However, in this design the cam and the cam follower are not contained between the sheaves, and a separate collar is required.